It may be true that fatherlessness begets fatherlessness, but widespread illegitimacy is a recent phenomenon whose ultimate causes demand inquiry. In his landmark 1965 report, “The Negro Family: A Case for National Action,” Daniel Patrick Moynihan observed that “both white and Negro illegitimacy rates have been increasing, although from dramatically different bases. The white rate was 2 percent in 1940; it was 3.07 percent in 1963. In that period, the Negro rate went from 16.8 percent to 23.6 percent.”

The 2011 figures (which exclude Hispanics) were 29.1% for whites and 72.3% for blacks–a more than eightfold increase for whites and more than threefold for blacks. A cycle of fatherlessness operating over two to three generations cannot be sufficient to explain such an enormous rise.

So what does? In our view, a dramatic change in incentives owing to two major social changes that were just getting under way when Moynihan wrote.

The first is the rise of female careerism–the expectation that most women will spend most of their adult lives (rather than just the period when they are single) in the workforce. Women have less incentive to wed, since marriage no longer means trading in a job for a provider husband. Female careerism got a big boost with the enactment of the Civil Rights Act of 1964, which prohibits sex discrimination in the workplace.

The second is the introduction of the pill, which the Food and Drug Administration approved for contraceptive use in 1960. It made nonmarital sex far more easily available, reducing the incentive for men to marry. As George Akerlof and Janet Yellen argued in a 1996 paper (yes, that Janet Yellen, and Akerlof is her husband), the pill very quickly broke down the old institution of the shotgun wedding. With reproduction under female control, it became a female responsibility. Men no longer felt obligated to marry women by whom they fathered children. The paradoxical-seeming result is that a technology to reduce “unwanted pregnancy” massively increased out-of-wedlock births.

That brings us back to the moralistic fallacy for which we faulted Hymowitz in our column last month. Completely absent from her analysis of why boys fail to grow up into “reliable husbands and fathers” is the crucial factor of female choice. If young women are less apt to marry because they are focused on education and career, and more willing to engage in sexual relationships unaccompanied by marriage or the expectation thereof, the incentives for young men are dramatically different.